It is very common to use artificial insemination on cattle animals. Success of artificial insemination depends highly on accurate identification of the term in which an animal is in estrus. Therefore it is important to have reliable information regarding the estrus term to ensure a successful insemination resulting in pregnancy. The economic importance of the matter gives rise to many different products and methods assigned to detect estrus.
It is known that during estrus the behavior of the cattle animal changes and the over all activity rises. This high activity manifests itself by walking, running, trying to ride other animals and the like. This high activity level is clearly different from the normal activity level of cattle animals, which spends most of the time eating and ruminating. Measuring of the level of activity, that is measuring the level of movement of the body of the animal, is known in the art and may be done by one of known sensors or methods, such measuring the RMS value of a signal produced by a sensor measuring the movements of the animal.
Products for detecting estrus have been in the market for more than two decades. These products are of two types.
The first type includes simple mechanical devices. These products do not transfer the information to any central management system, and the farmer using them has to spend a lot of time in monitoring, finding and separating the cattle according to his findings. Additionally, those products are usually intended for one time use only and consequently a lot of work is involved in mounting and removing them on and from the monitored cattle animal. The reliability of those devices is generally low. For example, devices that detect if a cattle animal is trying to ride each other might help in detecting estrus. However, not all the cattle animals ride other cattle animals during estrus.
The second type includes computerized devices that contain a motion sensor and are mounted on the animal (leg or neck). The leg mounted device count steps. This device might not give accurate information because the animal's leg is not always the most active part of the animal during estrus. In addition, mud tends to stick and harden on the device and cause discomfort and injury. Mounting the device on the leg is not easy. The neck mounted device measures general motion. The animal's neck participate in many activities such as eating, smelling and playing, so a high neck activity exists also when the animal is not in estrus. This of course makes it very difficult to detect the specific activity during estrus, and prevents neck-based sensors from acquiring accurate information.
A glass cell holding electrodes and a drop of mercury is a known technology to measure activity. When motion exists the mercury covers the electrodes and causes the impedance to drop.
A metal ball that creates an electromagnetic field when changing location is also a known technology to measure activity.
Acceleration sensors based on the piezoelectric affect is another known technology to measure activity. Yet, gravity affects such sensors so that the sensor inclination affects and changes the reading.
U.S. Pat. No. 4,846,106 describes an electronic switch mounted on the cow hind and activated when another cow rides it.
U.S. Pat. No. 4,247,758 describes a device that measures and indicates the number of movements of the animal activity for detecting estrus.
U.S. Pat. No. 4,618,861 describes a device that measures activity of an animal, and uses the device's motion for its source of energy.
U.S. Pat. No. 5,111,799 describes an electronic switch attached to the cow's hind and activated when another cow mounts it.
None of these references suggests a method for detecting estrus by combining additional information of the eating periods of the animal and/or it's head inclination with information regarding the animal's motion to detect estrus.